Novel synthetic multi-segmented fibers

ABSTRACT

MENTS HAVING AN AVERAGE SPACE THEREBETWEEN OF AT LEAST 0.1U AT LEAST ON THE PERIPHERY OF THE UNITARY MULTI-SEGMENTED FIBER CAN BE PRODUCED. WHEN A PART OF POLYAMIDE OR POLYESTER IS REMOVED FROM THE MULTI-LAYER STRUCTURE, A FIBER HAVING A SILK-LIKE DEEP GLOSS AND HIGHLY IMPROVED WATER ABSORBING PROPERTY AND TOUCH CAN BE OBTAINED.   A NOVEL SYNTHETIC MULTI-SEGMENTED FIBER HAVING A TOUCH SIMILAR TO NATURAL FIBER, AN EXCELLENT WATER ABSORBING PROPERTY AND AN IMPROVED GLOSS, WHICH COMPRISES AT LEAST 10 FINE SEGMENTS WHICH ARE COMPOSED OF AT LEAST ONE COMPONENT OF FIBER-FORMING LINEAR POLYAMIDE AND POLYESTER, EXTEND SUBSTANTIALLY CONTINUOUSLY ALONG THE LONGITUDINAL DIRECTION OF THE FIBER AND OCCUPY AT LEAST A PART OF THE PERIPHERY OF THE UNITARY MULTI-SEGMENTED FIBER, SAID FINE SEGMENTS HAVING THEIR CROSS-SECTIONAL SHAPES AND AREAS IRREGULAR AND UNEVEN TO EACH OTHERS, AND ADJACENT SEG-

Oct. 24,19 72 MASAO MATS ETA'L' 3,100,545

NOVEL SYNTHETIC MULTI-SEGMENTED FIBERS Filed Nov. 12, 1969- v I asneets-sheet 1 ig.1 A Fig.2 Fig.3 I 7 A B ,7 y

Oct. 24, .1972 I MASAO MATSUl ET AL I 3,700,545

NOVEL SYNTHETIC MULTI-SEGM ENTED FIBERS Filed NOV. 12; 1969 8 Sheets-Sheet 4 Och, A suyi ET NOVEL SYNTHETIC MULTI-SEC-MENTED FIBERS .Fi1e d Nov. 12, 1969 8 Sheets-Sheet 5 '03 Run "2 MASAO MATSUI ET AL 3,70%0545 NOVEL SYNTHETIC MULTI TSEGMENTED FIBERS 8 Sheets-Sheet ,6 I

Filed Nov. 12, 1969 3 .IO' lo" Oct. 24, 1972 MAsAo MAT SUI ET L 3,700,545

NOVEL SYNTHETIC MULTI-SEGMENTED FIBERS 8 Sheets-Sheet 7 Filed Nov. 12, 1969 Oct. 2 4, MASAQ su ET AL 3,700,545 NOVEL SYNTHETIC IMULTI'SEGMENTED'IFIBERS' Filed Nov.- 12, 1969 8 Sheets-Sheet iIJnited States Patent 3,700,545 NOVEL SYNTHETIC MULTI-SEGMENTED FIBERS Masao Matsui, Takatsuki, Susumu Tokura, Osaka, and Masahiro Yamabe, Neyagawa, Japan, assignors to Kanegafuchi Boseki Kabushiki Kaisha, Tokyo, Japan Filed Nov. 12, 1969, Ser. No. 875,673 Claims priority, application Japan, Nov. 13, 1968, 43/ 83,151; July 31, 1969, 44/ 60,893, 44/ 60,894, 44/ 60,895

Int. Cl. D01d 5/28 US. Cl. 161-175 28 Claims ABSTRACT OF THE DISCLOSURE A novel synthetic multi-segmented fiber having a touch similar to natural fiber, an excellent water absorbing property and an improved gloss, which comprises at least fine segments which are composed of at least one component of fiber-forming linear polyamide and polyester, extend substantially continuously along the longitudinal direction of the fiber and occupy at least a part of the periphery of the unitary multi-segmented fiber, said fine segments having their cross-sectional shapes and areas irregular and uneven to each others, and adjacent segments having an average space therebetween of at least 0.1 4 at least on the periphery of the unitary multi-segmented fiber can be produced. When a part of polyamide or polyester is removed from the multi-layer structure, a fiber having a silk-like deep gloss and highly improved water absorbing property and touch can be obtained.

The present invention relates to novel synthetic multisegmented fibers and methods for producing said fibers.

The conventional synthetic fibers have demerits that they have a waxy touch and are poor in water absorbing property and gloss as compared with natural fibers. In order to improve these demerits, a large number of mixspinning processes and surface treating processes have been heretofore proposed but any satisfactory means has never been developed.

The object of the present invention is to provide novel fibers having a natural fiber-like touch, an excellent water absorbing property and an improved gloss and methods for producing said fibers. The other objects will be easily understood from the following explanation.

The synthetic multi-segmented fibers of the present invention are manufactured by forming raw fibers, wherein the monofilament is composed of fiber-forming polyester and polyamide and has a layer-multiplied grainy, nebulous or archipelagic structure at least in a part of the cross-section and then removing at least a part of the polyester or polyamide from the raw fibers whereby ridges or fibrils at least on the fiber surface are formed by the remaining portion of the polyester or polyamide in the layer-multiplied structure.

Namely the present invention consists in a novel synthetic multi-segmented fiber having a touch similar to natural fiber, an excellent water absorbing property and an improved gloss, which comprises at least 10 fine segments which are composed of at least one component of fiber-forming linear polyamide and polyester, extend substantially continuously along the longitudinal direction of the fiber and occupy at least a part of the periphery of the unitary multi-segmented fiber, said fine segments having their cross-sectional shapes and areas irregular and uneven to each others, and adjacent segments having an average space therebetween of at least 0.1 preferably 0.1 to 1; at least on the periphery of the unitary multisegmented fiber.

The method for producing the synthetic multi-segice mented fibers comprises spinning a multi-segment spinning material having a cross-section of grainy, nebulous or archipelagic structure obtained by joining and dividing repeatedly in different phase, a polyester and a polyamide, solely or in conjugation with another spinning material composed of a single component and having a homogeneous cross-sectional structure, and treating the resulting filament with an alkali or an acid to decompose or dissolve and remove at least a part of the polyester or the polyamide.

Some terms used herein will be explained hereinafter.

The word fiber structures means filaments, staple fibers, yarns and structures formed from these materials, such as knitted goods, woven fabrics, webs and the like.

The word layer-multiplied structure means a structure wherein at least two components are mixed or adhered forming a large number of layer segments in a unitary filament and main segments thereof extend substantially continuously along the longitudinal direction of the filament.

Among the layer-multiplied structures, specifically the word layer-multiplied grainy structure means a structure wherein a large number of thin layer segments extending substantially continuously along the longitudinal direction of the unitary fiber (filament or staple fiber) are arranged one another as grainy layers. The main thin layer segments in the cross-section of the fiber have a fairly large width, for example, a width of 0.2 to 3 times, preferably 0.5-1.0 times the diameter of the unitary filament and a substantially uniform thickness and the segments extend, for example, in the case of filament at least several centimeters, usually more than several hundred centimeters in the longitudinal direction of the filament. Such a continuous state is referred to as substantially continuous in the specification and the claims.

The word layer-multiplied archipelagic structure means a structure wherein the predominant segments composed of one component have their more or less flat cross-sectional configuration and arranged in the crosssection of the fiber as if islands exist in an ocean.

The word layer-multiplied nebulous structure means a structure wherein most of the segments composed of one component are substantially circular in the crosssection and arranged in the cross-section of the fiber as if stars disperse in nebula.

The fibers having the above described layer-multiplied structures are referred to as raw fiber in the specification and claims.

The raw fibers having these layer-multiplied structures, for example, a multi-layered filament, i.e.. the filament having a multi-segment structure, can be obtained by layer-multiplying and spinning at least two spinning materials.

For a better understanding of the invention, reference is taken to the accompany-ing drawings, wherein:

FIG. 1 is a model diagram for illustrating a basic method of layer-multiplying two spinning materials into multi-layers;

FIG. 2 is an enlarged cross-sectional view of a twolayer filament;

FIG. 3 is an enlarged cross-sectional view of a fourlayer filament;

FIGS. 4 and 5 are enlarged cross-sectional views of raw fibers having a layer-multiplied grainy structure to be used in the invention;

FIG. 6 is an enlarged cross-sectional view of a raw fiber having a layer-multiplied archipelagic structure to be used in the invention;

FIG. 7 is an enlarged cross-sectional view of a raw fiber having a layer-multiplied nebulous structure to be used in the invention;

FIG. 8 is a perspective view showing flow of spinning materials in a network-of-passage type layer-multiplying mixer;

FIG. 9 is a vertical sectional view of a spinneret provided with a network-of-passage type layer-multiplying mixer suitable for the production of raw fibers having a layer-multiplied grainy structure;

FIGS. 10, 11 and 12 are cross-sectional views of the spinneret shown in FIG. 9 taken on lines 'I-I', II-II and III-III in the arrow direction, respectively;

FIG. 13 is an enlarged cross-sectional view of a trilobal raw fiber having a layer-multiplied grainy structure to be used in the invention;

FIGS. 14, 15 and 16 are enlarged cross-sectional views of composite raw fibers having a layer-multiplied grainy structure portion and a structure portion composed of a single fiber-forming component in a unitary filament;

FIG. 17 is a vertical sectional view of a spinneret provided with a different type of layer-multiplying mixer suitable for the production of raw fibers to be used in the invention;

FIGS. 18, 19 and 20 are cross-sectional views of the spinneret shown in FIG. 17 taken on lines I-I', II-II and III-III in the arrow direction, respectively;

FIG. 21 is an enlarged cross-sectional view of a trilobal raw fiber having a layer-multiplied nebulous structure to be used in the invention;

FIGS. 22, 23 and 24 are enlarged cross-sectional views of composite raw fibers having a layer-multiplied archipelagic or nebulous structure portion and a structure portion composed of a single fiber-forming component in a unitary filament;

FIG. 25 is an enlarged cross-sectional view of a conventional two-component composite filament composed of 6 triangular segments; and

FIG. 26 is a side elevational view of multi-segmented fibers of the invention in an enlarged scale, taken from a photomicrograph.

Referring to FIG. 1, two spinning materials (A and B) are joined at a point I, to form a two layer structure (AB), which is divided at a point S and then the divided spinning materials are again joined at a point J to form a four layer structure (ABAB). Embodiments of the two layer structure and the four layer structure are shown in FIGS. 2 and 3 respectively. In order to increase the number of the segments as in this manner, the division at the point S should be effected so as to remain the joined state at the point J at least partially, preferably completely and the joining at the point J should be effected so as to add the number of the segments at least partially, preferably completely. This purpose can be attained by varying the direction of joining at the point J and the direction of division at the point S, preferably by 90". Such a joining-dividing is referred to as joining-dividing in different phase. When the joining-dividing as shown in FIG. 1 is carried out n times in multi-stage, the number of the resulting layer segments is calculated to be 2. Of course, the above described number of layer segments is a calculated value and in fact the spinning materials flow irregularly or stand in the reservoirs and the passages and consequently the layer segments are broken or cohere and the above number often deviates from the calculated value. Furthermore, it is needless to say that FIG. 1 shows a fundamental type and there are numerous applications or modifications thereof (the fundamental type may be modified or two or more types may be combined).

By these multi-stage of joining-dividing steps in different phase, two or more spinning materials can provide easily layer multiplied fibers. The shape of cross-section of the layer-multiplied fibers varies depending upon the structure of the layer-multiplying mixer and the nature and combination of spinning materials. A combination of spinning materials having a very high mutual aifinity, for example, nylon-6/nylon-66, polyethylene terephthalate/polyethylene oxybenzoate and the like, in most cases provides the grainy segment structures as shown in FIGS. 4 and 5. However, a combination of a polyamide and a polyester, for example, nylon-6/ polyethylene terephthalate does not always provide the grainy structure, because the aflinity of both the components is poor. In the combination of a polyester and a polyamide, when the number of (n) of joining-dividing steps is small, the grainy segment structure can be obtained and as the number increases, the layers are apt to be broken in the cross-section to result the archipelagic structure as shown in FIG. 6 and when the number further increases, the nebulous structure as shown in FIG. 7 is formed. The condition wherein the grainy structure, the archipelagic structure or the nebulous structure is formed, depends upon the nature of the spinning materials and the structure of the layer-multiplying mixer.

However, even in the combination of a polyester and a polyamide, the grainy segment structure can be easily formed by using an appropriate mixer.

The inventors have already proposed a layer-multiplying mixer comprising spinning material reservoirs arranged in a multi-stage and narrow passages connecting these reservoirs, in the copending US. patent application Ser. No. 711,070 filed on Mar. 6, 1968 now abandoned and another layer-multiplying mixer comprising three dimensional network of narrow passages, in the copending US. patent application Ser. No. 783,508 filed on Dec. 13, 1968 now Patent No. 3,613,173.

Even though the above described multi-stage reservoir type mixer can provide the grainy structure (particularly small reservoirs are effective), the network-of-passage type mixer is more useful for obtaining the layer-multiplied grainy structure. The network-of-passage type mixer can provide the grainy structure within and over broad ranges of the combination of spinning materials and the number of joining-dividing steps (n).

- In FIG. 8, two spinning materials A and B are joined at J and are divided at S in a direction dilferent from the joined direction by and then joined again at 1 divided at S and joined at J On a plane U, the first stage of joining is effected, on a plane U the second stage of joining-dividing is effected and on a plane U the third stage of joining-dividing is effected. In this manner, the layer-multiplying mixer having any stage number of joining-dividing can be constituted.

One embodiment of the spinneret provided with such network-of-passage type layer-multiplying mixer will be explained with reference to FIGS. 9-12.

A spinning material feeding unit 0 is arranged on a layer-multiplying mixer consisting of a plurality of successively superposed disk-shaped mixer units 10, 20, 30, 40 and 50, and a spinneret plate is arranged under the layer-multiplying mixer having an intervenient layermultiplied spinning material delivering unit 60. These elements are assembled integrally by a cylindrical holder 110. As shown in FIG. 10, the spinning material feeding unit 0 is provided with a cylindrical central reservoir 1 and an annular reservoir 2 concentrically surrounding the central reservoir 1. Ducts 3 communicating two reservoirs 1 and 2 are provided radially at a boundary portion of the feeding unit 0 and the mixer unit 10. The mixer unit 10 is provided with vertical conduits 11 which open at the middle portion of the ducts 3 and communicate with dividing-joining passages 12 arranged at the bottom surface of the mixer unit 10. The dividing-joining passages 12 have a shape as shown in FIG. 11. The connecting points of the vertical conduits 21 in the 2nd stage mixer unit 20 and the dividing-joining passages 12 of the 1st stage mixer unit 10 are shown by the dotted line circles 21. The mixer units 10, 20, and 50 have the same structure, but the adjacent units should be arranged in such a relation that the arrangements of the dividing-joining passages of both units are somewhat shifted and the middle portion of the passage of the upper unit coincides with the vertical conduit of the lower unit. The spinning material delivering unit 60 is provided with vertical conduits 61, the number of which is the same with that of vertical conduits of the mixer unit. The vertical conduits 61 open to the dividing-joining passages of the last stage mixer unit 50 and further communicate with orifices 102 through a reservoir 101 provided at a boundary contacting portion of the spinning material delivering unit 60 and the spinneret plate 100. FIG. 12 shows that the orifices 102 are arranged on a common circumference. The number of orifices 102 may be same with or different from that of vertical conduits 61. When the number of orifices 102 is same with that of vertical conduits 61, the reservoir 101 can be omitted. It is not always necessary that the orifices 102 are arranged on the common circumference, but the orifices 102 can be arranged in an arbitrary arrangement. The cross-sectional shape of the orifice 102 may be circular or non-circular.

In the spinneret provided with the above described network-of-passage type layer-multiplying mixer, two spinning materials are fed separately into reservoirs 1 and 2 in a predetermined mixing ratio. The two spinning materials in the reservoirs 1 and 2 are joined at the middle portion of the duct 3, passed through the vertical conduit 11, and then subjected to joining-dividing in different phase in the dividing-joining passage 12, and flowed into the vertical conduit 21 of the mixer unit 20. In the same manner, the spinning materials are repeatedly subjected to 6 times of joinings, and the layer-multiplied spinning materials are flowed into the reservoir 101 and then extruded through the orifice 102 on the spinneret plate 100. FIG. 13 shows a cross-section of filaments having a non-circular cross-section extruded from Y-shaped orifices. A flow of layer-multiplied spinning material, in this instance, a flow from a vertical conduit 51 in FIG. 9, and a flow of one component spinning material having no such a layer-multiplied structure (polyamide, polyester and other Wellknown spinning materials) can be conjugated just before they are extruded through an orifice. FIGS. 14-16 show cross-sections of fiber (unitary filament) obtained by the above method. FIGS. 14, 15 and 16 show cross sections of filaments of side-by-side conjugation type, eccentric sheath-core conjugation type and of concentric sheath-core conjugation type, respectively.

It will be apparent from the above explanation that the raw fibers having a layer-multiplied grainy structure can be easily produced by means of a spinneret having a very simple structure.

Most of the raw fibers obtained by the use of the spinneret provided with a network-of-passage type mixer as shown in FIG. 9 have a distorted grainy structure. FIG. 5 shows a cross-section of a raw fiber having a distorted grainy structure, and FIG. 4 shows that of a raw fiber having an undistorted uniform grainy structure. The distorted grainy structure is extremely preferred for the improvement of the touch of fibers, which is the object of the invention because, the number of ridges on the peripheral surface of the fiber developed in an after-treatment becomes large. For example, in the raw fibers having a distorted grainy structure as shown in FIG. 5, the number of segments exposed on the raw fiber surface, which can be formed into ridges by an after-treatment, is 2-5 times larger than that of fibers having a uniform grainy structure, and moreover the exposed segments are distributed all over the peripheral surface of the fiber. On the contrary, in the fiber having a uniform grainy structure, the number of ends of segments exposed on the raw fiber surface is few and the end position biases. In particular case, the ends of segments converge at two points as shown in FIG. 4.

When polyester and polyamide are mix spun by using a spinneret provided with a layer-multiplying mixer comprising reservoirs and passages as disclosed in the above copending U.S. patent application Ser. No. 711,070 filed on Mar. 6, 1968, now abandoned, for example, by using 6 a spinneret as shown in FIG. 17, the grainy structure, the archipelagic structure and the nebulous structure have been usually obtained by 2-5 stages of joining-dividings, 5-8 stages of joining-dividings, and at least 8, particularly at least 9, stages of joining-dividings, respectively.

When polyester and polyamide are layer-multiplied, the polyamide often forms islands at the cross-section of raw fiber (unitary filament) having a layer-multiplied archipelagic structure or stars at the cross-section of raw fiber (unitary filament) having a layer-multiplied nebulous structure. This is presumably due to the fact that polyamide coheres more easily than polyester at the melting. Of course, the island and the sea, or the star and the sky (background) are not always arranged in the above relation, but both of islands (or stars) of polyester and islands (or stars) of polyamide may often coexist at the crosssection. Furthermore, such a double segment structure that islands of polyester are located in islands of polyamide is often formed.

It is not always necessary in the invention that the layer-multiplied segment structure is completely continuous along the fiber axis, but substantially continuous structure can attain the object of the invention. That is, when the main segments are continuous over a suificient length (for example, from several centimeters to more than several meters), the object of the invention can be attained.

Another embodiment of spinning process of layer-multiplied raw fibers (filaments) of the invention will be explained with reference to FIGS. 17-20, hereinafter.

A spinning material feeding unit 0' is arranged on a layer-multiplying mixer consisting of a plurality of successively superposed disk-shaped mixer units 10', 20, 30 and 40, and a spinneret plate is arranged beneath the layer-multiplying mixer. These elements are assembled integrally by a cylindrical holder 110. A cylindrical central reservoir R and an annular reservoir R concentrically surrounding the central reservoir R are arranged at a boundary contacting portion of the spinning material feeding unit 0' and the mixer unit 10. The mixer units 10', 20', 30 and 40' have the same structures. The mixer unit 10' is provided on the upper surface and the lower surface with cylindrical central reservoirs R and R respectively, and with annular reservoirs R and R concentrically surrounding the central reservoirs respectively. As shown in FIG. 18, the mixer unit 10' is provided with radially arranged ducts 13, which connect the reservoirs R with R on the upper surface. Vertical conduits 14 extend downwardly and vertically from the middle portions of the ducts 13 and open to distributing passages 15 or 16. The distributing passages 15 and 16 connect the lower openings of the vertical conduits 14 alternately with the central reservoir R and with the annular reservoir R at the lower surface of the mixer unit 10. Partition plates 111 are interposed between two adjacent mixer units, between the spinm'ng material feeding unit 0' and the mixer unit 10, and between the mixer unit 40' and the spinneret plate 100. The partition plate 111 is provided at the center portion and at a portion corresponding to the annular reservoir with apertures 112 and 113 respectively, whereby two reservoirs faced each other are communicated. In the spinneret plate 100', the vertical conduits form orifices 102 at the lower end and open at the lower surface. The structure of the upper surface of the spinneret plate 100 is the same with that of the mixer unit.

In the above described spinneret, two spinning materials are fed into reservoirs R and R in a predetermined mixing ratio. The two spinning materials in the reservoirs R and R are joined at the middle portion of the duct 13, and a part of the joined spinning materials fiows into the reservoirs R through the vertical conduit 14 and the distributing passage 15, and another part of the joined spinning materials flows into the reservoir R through the vertical conduit 14 and the distributing passage 16. The spinning materials in the reservoir R flow into the duct 23 of the second stage mixer unit 20' through the reservoir R and the spinning materials in the reservoir R flow into the duct 23 of the second stage mixer unit 20' through the reservoir R and these two spinning material flows are joined at the middle portion of the duct 23. Then a part of the joined spinning material flow goes into the reservoir R and another part of the joined spinning material flow goes into the reservoir R In this spinneret, the joining is effected in the ducts 13, 23, etc., and the dividing is effected in the reservoirs R R R R etc. That is, as seen from FIG. 18, spinning materials in a reservoir are divided, when the spinning materials fiow into a plurality of ducts 13 from the reservoir. The dividing direction is the same with the arrangement direction of ducts 13, i.e., the circumferential direction. The joining direction in the ducts 13 is diametrical direction. Thus, the dividing direction and the joining direction are perpendicular.

In this spinneret, orifices having a non-circular crosssection can also be used as in the case of a spinneret provided with a network-of-passage type layer-multiplying mixer. FIG. 21 shows a cross-sectional shape of trilobal raw fibers extruded through orifices having a Y-shaped cross-section.

The spinneret as shown in FIG. 17 is an embodiment of spinneret capable of carrying out the multi-stage of joining-dividing in different phase and even any other spinnerets, as far as they can effect the joining-dividing in different phase in multi-stage, can be used for the Object of the present invention.

The composite filaments having the cross-sections as shown in FIGS. 22 to 24 can be obtained by conjugate spinning a layer-multiplied spinning material and a single component spinning material.

The polyester-polyamide raw fibers obtained as described above, wherein at least a part of the cross-section has the layer-multiplied segment structure, have various excellent properties and if they are subjected to a succeeding chemical treatment, they can provide with excellent properties, particularly the natural fiber-like touch, water absorbing property and gloss. Namely, ridges can be developed on the periphery of the fiber by decomposing and removing at least a part of polyester in the above polyamide-polyester rnulti-layer segment structure with an alkali or dissolving and removing at least a part of polyamide in the multi-layer segment structure with an acid. Alternatively by the above described treatment, the raw fibers are divided into fine fibrils (hereinafter referred to as fibrillation).

The amount of polyester or polyamide removed from the polyester-polyamide multi-layer segment structure of the raw fibers is preferred to be at least 1%, more particularly at least 3% based on the weight of multi-layer segment structure portion. The more preferable amount is at least 5%. As the polyester or polyamide is decomposed (or dissolved) and removed from the raw fibers, the segments remained after the dissolution form ridges on the fiber surface, which have at least 0.1 of space between each other. When the dissolution amount of segments is comparatively large, the spaces between the ridges grow to about 1a and more preferable multi-segmented fibers are resulted, and if such a dissolution progresses, the above described spaces become larger gradually and the fibers are fibrillated. If the polyester or polyamide is completely removed, multi-segmented fibers consisting of polyester fibrils or polyamide fibrils having a very fine denier can be obtained. As the ridges develop or the fibrillation progress, the fibers show improved water absorbing property and desirable natural-fiber-like touch or hand and gloss.

The amount of polyester or polyamide removed when the fibrillation stars, varies depending upon the structure of the raw fibers and the mixing ratio of these polymers but in many cases the amount is about 15 to 50% by weight based on the total amount of the layer-multiplied portion. Even if the amount is less than 15% by weight and the fibrillation does not substantailly occur, the touch of the multi-segmented fibers is highly improved and the gloss is fairly improved. The completely fibrillated multisegmented fiber structure has a very soft and flexible touch and an improved gloss. The dissolution (removal) of the polyester or polyamide depends upon the kind and concentration of alkali or acid, pH, temperature or time of reaction but the conditions can be selected optionally depending upon the object. The selection of the reaction condition is easy to those skilled in the art.

The properties of the multi-segmented fiber srtucture are fairly varied by the amount of polyester or polyamide removed from the multi-layer structure portion of the raw fibers and therefore such an amount can be selected depending upon the object. In order to provide the water absorbing property and improved touch to the fiber structure, the amount of polyamide or polyester removed is 2.5 to 15 by weight based on the total layer-multiplied structure portion and particularly the effect appears remarkably in at least 3% by weight. Even in such an amount, a satisfactory water absorbing property can be provided to the fiber structure and the strength and the dyeing afiinity do not substantially decrease and the loss due to the decreased amount can be minimized.

In order to obtain a silk-like deep gloss, and highly improved Water absorbing property and touch by increasing the spaces between the remained segments on the peripheral surface of the fiber to develop ridges sharply or by fibrillating the fibers at least partially, the amount of polyamide or polyester removed is preferred to be 10 to 50% based on the total multi-layer structure portion, more particularly 15 to 35%. If the amount exceeds 50%, the resulting structure is too fibrillated and becomes excessively flexible and therefore such a structure is not suitable for material of clothing and is disadvantageous in view of the decreases of strength and dyeing affinity and the large Weight loss. However, in order to obtain a particular fiber structure having very excellent water absorbing property, flexibility and gloss resulted from a high fibrillation, the amount of polyamide or polyester removed may be more than 50% by weight based on the total multi-layer structure portion.

The alkalis to be used for the object of the present invention may be those which can hydrolyze the polyester without corroding the polyamide so much and for example, inorganic bases, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate and the mixtures thereof are useful. Organic bases, such as amines, diamines may be employed.

The acids to be used according to the method of the present invention may be those which dissolve the polyamide at least partially but do not corrode the polyester so much. For example, organic acids, such as formic acid, acetic acid and the like, inorganic acids, such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and the like, the mixtures thereof, the mixtures of these acids with salts can be used together with solvents, such as water, organic or inorganic compounds. Of course, the solvents, such as water may be omitted.

The structure of the raw fibers highly influences the properties of the resulting multi-segmented fiber structure. Even if the fibers having no multi-layer segment structure are treated with such a compound, the water absorbing property, touch, hand, gloss and the effect of fibrillation are not improved. Furthermore, if the number of the segments is few, the desired effect cannot be attained. In order to attain the object of the present invention, the raw fibers must have a sufficient number of segments. In this point, the ridges developed or fibrils formed by removal of a part of one component segment in the grainy structure portion are similar to the structure of the natural fiber surface and such a structure is very preferable. The ridges developed or fibrils formed 9 from the distorted grainy structure are irregular but are vqy similar to the structure of the natual fiber and such a structure is rather very preferable.

In order to develop a sufficient number of ridges on the peripheral surface of the fiber or to effect the fibrillation sufficiently, it is necessary that the multi-layer segment structure portion of the raw fibers has at least 10, preferably at least 20, more particularly at least 30 segments in the cross-section of the unitary multi-segmented fiber. In order to obtain preferable gloss, the average dimension of the segments or the average width of the ridges is desired to be 0.1 to 10p. and particularly to be substantially the same degree as the wave length of visible ray, that is about 0.1 to 111-.

Furthermore, it is necessary that the ends of at least segments, preferably at least 20 segments expose on the raw fiber surface or are near the fiber surface. The term the ends of segments are near the fiber surface used herein means that the ends exist within a distance of less than preferably less than 5% of the average diameter of the unitary multi-segmented filament, from the peripheral surface, that is the ends are enough near the peripheral surface and able to expose easily by the after-treatment. The mixing ratio of polyamide-polyester in the multi-layer segment structure portion of the raw fiber can be optionally selected depending upon the object but in many cases, the ratio of 1/10 to 10/ 1, preferably of 1/ 3 to 3/1 can bring about good results.

The shape and dimension of islands in the layer-multiplied archipelagic structure are generally irregular but this fact results in formation of a complicated structure of the multi-segmented fiber after the treatment and such a structure is similar to the structure of the natural fiber. so that such a fact is desirable for the object of the present invention. The shape of islands in the layer-multiplied archipelagic structure of the raw fiber is different from one another and the dimension of these islands is different about 1/20-30 in the area ratio and the number of islands in the cross-section of the raw fiber (unitary filament) is about 10 to 100. Such raw fibers are suitable for the object of the present invention and can be easily produced. Also, in the layer-multiplied nebulous raw fibers, the shape of star segments is different from one another and the dimension is different about 1/ -30 in the cross-sectional area ratio and the number of star segments in the cross-section of the raw fiber is about 100 to 10,000. Such a raw fiber is suitable for the object of the present invention and can be easily produced.

In order to obtain the fibers of the present invention, the raw fibers having the layer-multiplied grainy, archipelagic or nebulous structure are selected and used depending upon the object. Similarly, the mixing ratio of polyester-polyamide in the multi-layer structure portion in the raw fiber can be selected optionally.

Now, it has been well-known that the filaments having non-circular cross-section, for example, triangular or multilobal cross-section have a high gloss. The gloss of the known filaments having non-circular cross-section utilizes the effect of highlight due to reflection face provided by metal yarns and the like. As the more improved method, a process wherein two components are conjugate spun and then one component is removed or the filament is divided into 2 to 8 filaments to form a filament having sharp angles has been proposed. For example, U.S. Pat. No. 3,117,362 discloses that a multilayered filament composed of segments having sharp edges as shown in FIG. is subjected to a physical treatment or a dissolution treatment to separate into each segment to form fibers having silk-like gloss and an improved bulkiness. This process permits to produce fibers having a little more fine denier than the conventional non-circular filament but the fiber structure shown in the above U.S. patent is obtained by only one step of conjugate spinning and in fact it is impossible in view of the spinneret structure to increase the number of segments considerably or to make the fineness of the mono-segment very small, and accordingly only a simple shape of segment is obtained. The segments shown in the U.S. patent have a relatively simple structure and the fineness is more than 0.1 denier. On the other hand, the fineness of the segments or fibrils in the multi-segmented fibers of the present invention can be smaller as mentioned above. The multi-segmented fibers of the present invention consist of a large number of segments or fibrils having irregular and uneven cross-sectional shapes, uneven crosssectional area and fine denier. The gloss of the multisegmented fibers of the present invention is due to light reflection of a large number of fibrils having different shapes and sizes or sharply developed ridges and has a large depth. This is essentially different from the metallic gloss exhibited by the non-circular cross-sectional filament or the filament disclosed in the above U.S. patent. It is mentioned that the fibers disclosed in the above U.S. patent are excellent in view of the bulkiness but they are simple in the cross-section or the surface and therefore they do not have any ridges, complicated structure and desirable touch similar to the natural fibers as in the multi-segmented fibers of the present invention.

The multi-segmented fibers of the present invention, particularly the fibers partially fibrillated before the complete fibrillation or the fibers developed ridges sharply show a surprisingly high similarity to the natural fibers. The method of the present invention facilitates manufacture of the fibers having no waxy touch inherent to the synthetic fibers. Furthermore, the fabrics or yarns composed of the conventional synthetic fibers do not make a sound in friction but the fabrics or yarns composed of the multi-segmented fibers of the present invention make a sound similar to silk in friction. Moreover, the multisegmented fibers of the present invention have a highly improved water absorbing property as compared with the conventional synthetic fibers. For example, when the water content ratios of various fibers, when they are immersed in water at room temperature for more than 6 hours and then worked in a centerifugal separator having a high power, are determined, those of nylon-6 fibers are 8 to 10% and those of polyethylene terephthalate fibers are 2 to 5%, while the multi-segmented fibers of the present invention shows those of more than 15% and among them, some fibers show no less than 20%.

On the contrary, the conventional non-circular crosssectional fibers and the fiber obtained by separating a small number of segments having a simple shape are not substantially different in the water absorbing property from the conventional circular cross-sectional fibers.

The polyamide to be used in the invention includes commonly known fiber-forming linear polyamides. For example, mention may be made of nylon-4, nylon-6, ny1on-7, nylon-11, nylon-12, nylon-66, nylon-610, polyhexamethylene isophthalamide (nylon-61), polyhexamethylene terephthalamide (nylon-6T), polyparaxylylenedodecaneamide (PXD12) and modified compounds thereof, copolymers thereof and polymer blends thereof.

Furthermore, alicyclic polyamides, such as polyamide (PACM-9) prepared from bis-p-aminocyclohexylmethane (PACM) and azelaic acid, a polyamide (PACM-l2) prepared from PACM and l,10-decamethylene dicarboxylic acid, and a polyamide prepared from 1,4-cyclohexane dicarboxylic acid and a straight chain diamine having 9-12 carbon atoms (for example, 1,1l-undecamethylenediamine), and copolyamides containing these polyamides as the main component may be effectively used for the object of the invention.

The polyester to be used in the invention includes commonly known fiber-forming linear polyesters, polyesteramides and polyester ethers. For example, mention may be made of polyesters, such as polyethylene terephthalate, poly 1,4 bishydroxymethylcyclohexane terephthalate and modified compounds thereof, copolymers thereof and polymer blends thereof; and polyester ethers,

11 such as polyethylene oxybenzoate and copolymers, modified polymers and polymer blends consisting mainly of polyethylene oxybenzoate.

Furthermore, polypivalolactone, one of polyesters, can also be used effectively in the invention. In the present invention the polypivalolactone means polymers con? taining at least 60% by weight, preferably, more than 80% by weight of polypivololactone. These polymers may contain a small amount of additives, such as stabilizer, pigment and plasticizer, and also these polymers may be the copolymer.

The stabilizer includes radical scavengers, such as octadecyl phosphite, etc., and conventional antioxidants, such as copper and manganese compounds and phosphorous acid compounds, etc. The plasticizer includes paraffin, polyolefin, modified polyolefin, polyalkylene oxide, etc. The comonomer to be copolymerized includes, for example, a,a-R R -B-propiolactone, wherein R and R represent methyl, ethyl, propyl and phenyl groups, and

amount. The two spinning materials were layer-multiplied and extruded through orifices 102 having a circular crosssection into air, cooled and wound up on a bobbin at a take-up rate of 600 m./min. after oiling. The wound undrawn filaments were drawn to 3.92 times their original length on a draw pin at 100 C. to obtain filaments P of 70 denier of 18 filaments.

The filaments F were dipped in 4% aqueous solution of sodium hydroxide kept at 90 C. in a bath ratio of 50 for 2-60 minutes as shown in the following Table 1 to hydrolyze PET, whereby multi-segmented filaments T -F were obtained, respectively. With respect to the multi-segmented filaments F -F the percentage of decreased weight based on the filament F the gloss and the water absorption percentage were determined and a result as shown in Table 1 was obtained. In Table 1, with respect to the gloss, the degree similar to gloss of silk was classified into three grades by naked eye, and similarly, with respect to the touch, the degree similar to touch of h lik 20 natural fiber was classified into three grades.

TABLE 1 Water Treating Decreased absorption time, weight. percentage, Sample min. percent Gloss Touch b percent Filament F1" 0 X X 5. 6 Filament F12 2 1. 2 A O 8. Filament Fri 5 3. 7 A O 9. 1 Filament F14 7. 6 A O 11. 3 Eilament F s 15 10. 5 O O 16. 4 Filament F 20. 5 O O 10. 5 Filament F11 31 O O 25. 0 Filament F 47 O A 37. 7 Filament FM 60 48 O A 37. 2

B Gloss O: Quite silk-like gloss. A: Fairly silk-like gloss. X: Conventional synthetic fiber-like gloss.

b Touch:

0.- Natural fiber-like touch. A: Very solt touch. X: Conventional synthetic fiber-like touch.

0 Control.

* Present invention.

The invention will be explained further in detail by the following examples.

In examples, water absorption rate and water absorption percentage were determined as follows:

(a) WATER ABSORPTION RATE A sample, such as a cloth or knitted goods, is washed thoroughly and dried, and about 0.2 cc. of water is dropped on the sample surface, and the time in second required for absorbing all the water is referred to as water absorption rate.

(b) WATER ABSORPTION PERCENTAGE A sample, such as a skein, cloth or knitted goods is washed thoroughly and dipped in water at 20 C. for more than 10 hours. The water absorbed sample is worked sufficiently in a centrifugal separator under a condition of 10,000 r.p.m., 30 min. and rotation radius of about 4 cm. The amount of water thus removed based on the weight of the dried sample is referred to as water absorption percentage.

Example 1 Nylon-6 having an intrinsic viscosity of 1.15 in mcresol at 30 C. and polyethylene terephthalate (hereinafter abridged as PET) having an intrinsic viscosity of 0.62 in o-chlorophenol at 30 C. were layer-multiplied, and then spun.

Namely, a spinneret as shown in FIG. 9, in which further five mixer units same as a mixer unit 50 were placed between the mixer unit 50 and a layer-multiplied spinning material delivering unit 60 (that is, the number n of stages of joining-dividing for layer-multiplying is 11), was used and kept at a temperature of 290 C. Melted nylon-6 and melted PET were fed into the reservoirs 2 and 1 respectively in the same Table 1 shows that when polyester in the multi-layer structure is partially or wholly removed by the hydrolysis, the water absorption percentage of the filament increases and further the touch and gloss are improved. The touch can be satisfactorily improved by removing small amount of polyester segments. However, it is preferable that more than 10% of polyester are removed in order to improve greatly the gloss and touch. The filaments F and F in which polyester segments have been removed substantially completely, have a quite soft touch.

Example 2 The nylon-6 and PET used in Example 1 were layermultiplied and spun. Namely, the two spinning materials were mix spun in a mixing ratio of 1/1 (weight ratio) and drawn in the same manner as described in Example 1, except that a spinneret as shown in FIG. 9 having the number n of stages of joining-dividing for layer-multiplying of 8 was used, to obtain filaments F of denier of 20 filaments.

Although the filaments F were extruded through orifices 102 having a circular cross-section, but microscopical examination showed that most of the actual crosssections of the filaments F were somewhat deformed. This is presumably due to the difference between the nylon-6 and the PET in the solidifying point and shrinking percentage.

The filament formed at a distance of 1 m. from the outlet of the orifice 102 had a particularly large crosssection area, which showed a distorted grainy structure.

Then, the above nylon-6 was spun through orifices having a circular or Y-shaped cross-section by means of a conventional spinneret kept at 290 C., cooled and wound up on a bobbin at a rate of 600 m./min. after oiling. The wound undrawn filaments were drawn to 3.92 times their original length to obtain drawn filaments F of 85 denier of 20 filaments having a circular crosssection or drawn filaments E, of 85 denier of 20 filaments having a trilobal cross-section.

The above PET was spun and wound up in the same manner as described in the above nylon-6, and theresulting undrawn filaments were drawn to 3.92 times their original length on a draw pin at 100 C. to obtain drawn filaments P of 85 denier of 20 filaments having a circular cross-section or drawn filaments F of 70 denier of 18 filaments having a trilobal cross-section.

The filaments F were treated with 4% aqueous solution of sodium hydroxide kept at 90 C. for 5, 30 and 60 minutes to obtain multi-segmented filaments F F and F respectively. In the filaments F 2.8% by weight of PET were hydrolyzed and a large number of ridges were observed microscopically on the surface. In the multisegmented filaments F about 50% by weight of PET were hydrolyzed and fairly large amount of fibrils were formed.

FIG. 26 shows a side-view of the multi-segmented filaments F In the multi-segmented filament F most parts of PET segments were hydrolyzed and nylon-6 segments were substantially fibrillated.

The multi-segmented filaments F F and F according to the present invention had a deep gloss similar to that of natural fiber, particularly, that of silk. On the other hand, the control samples, i.e., the filaments F and F had a simple gloss inherent to synthetic fibers, and the filaments F and F had a sharp and metallic gloss entirely different from "silk-like deep gloss. It will be apparent that although the filament F has a somewhat deformed circular cross-section, the gloss of the multi-segmented filaments F F and F is not caused by this deformed circular cross-sectional shape.

Example 3 The filaments F F and F obtained in Example 2 were knitted into half-stitched tricots T T and T by means of a tricot knitting machine of 28 gauges, respectively. Each of the tricots T and T was subjected to a soaping in a conventional manner, and dipped in 6% aqueous solution of sodium hydroxide kept at 180 C. for 2, 5, 15 or 30 minutes and then respective four kinds of the alkali treated tricots were washed with water. These alkali treated tricots T and T of each four kinds were dyed and subjected to a tenter finishing to obtain tI'iCOtS T21, T22: T23 and T24, and tI'ICOtS T61, T62, T63 and T respectively.

The tricot T was dyed and subjected to a tenter finishing to obtain a tricot T The tricots T -T according to the present invention had an excellent touch and a gloss similar to those Oif natural fiber, particularly, those of silk. While, the control tricots T -T as well as the tricot T had a waxy touch and a metallic gloss inherent to filaments having a non-circular cross-section.

With respect to the tIICOtS T21-T24, T41 and Tm rge, the percentage of decreased weight based on the original tricots T T and T in the above alkali treatment, and the water absorption rate are shown in the following Table 2.

Example 4 The filaments F F and F obtained in Example 2 were knitted into taffetas t t and t respectively.

The tafietas t and t had a waxy touch. The taffeta t had more improved and preferable touch than taifetas t and t but the touch was still insufficient.

The taffeta t was clipped in 20% aqueous solution of sodium hydroxide for 25 minutes to dissolve and remove PET, whereby a taffeta was obtained. Comparison of the weights of the tafietas t and t showed that substantially all (95%) of PET were dissolved and removed. The taffeta r according to the present invention had a partially delustered deep gloss different from sharp light-reflection gloss of the control taffeta t Moreover, the taffeta was different from the tafl'etas t and t in the touch, and had no waxy touch inherent to synthetic fibers.

The water absorption percentage and water absorption rate of the taffetas t t and t were determined in the same manner as described in Examples 1 and 2 and a result as shown in Table 3 was obtained.

TABLE 3 Water absorption Water percentage, absorbing 'Iafieta percent rate, sec.

Table 3 shows that the taffeta according to the present invention is considerably superior to the control taffetas t and t and the untreated taffeta t in the hydrophilicity or water absorbing property.

Example 5 Nylon-66 having an intrinsic viscosity of 1.1 in m-cresol 30 C. and a copolymer having an intrinsic viscosity of 0.6 in o-chlorophenol at 30 C., which was composed of by weight of polyethylene terephthalate and 10% by weight of polyethylene isophthalate, were used. A spinneret as shown in FIG. 9 having the number n of stages of joining-dividing for layer-multiplying of 5 was used. The nylon-66 and the copolymer were mix spun in a mixing ratio of 1/1 and drawn in the same manner as described in Example 1 to obtain filaments F of 45 denier of 12 filaments, the cross-section of which had a distorted grainy segment structure.

The filaments F were knitted into a tricot T The tricot T was treated in 4% aqueous solution of sodium hydroxide kept at 90 C. for 20 minutes to obtain a tricot The weight of the thus treated tricot T was about 25% smaller than that of untreated tricot T The tricot T prepared from synthetic multi-segmented fibers of the present invention had satisfactorily excellent touch, gloss and water absorbing property.

Example 6 Nylon-6 and PET used in Example 1 were layer-multiplied, and the resulting layer-multiplied spinning materials and polyethylene oxybenzoate (hereinafter abridged as PEOB) having an intrinsic viscosity of 0.61 in o-chlorophenol at 30 C. were conjugate spun to obtain filaments having a cross-section as shown in FIG. 15. Namely, in a spinneret kept at 290 C., the nylon-6 and the PET were subjected to 8 times of joining-dividing in diiierent phase in a mixing ratio of 1:1 (weight ratio), and the resulting layer-multiplied spinning materials and melted PEOB were bonded in an eccentric sheath-core relation so that the conjugate ratio was nylon-6/PET/PEOB=1/1/1 (weight ratio), and the bonded spinning materials were extruded through orifices. The extruded filaments were wound up and drawn in the same manner as described in Example 1 to obtain filaments F of 100 denier of 28 filaments.

The filaments F were treated with steam at 100 C. for 10 minutes in relaxed state to obtain crimped filaments F The crimped filaments F were knitted into a tricot T The tricot T was treated with 4% aqueous solution of sodium hydroxide kept at 90 C. for minutes to obtain a tricot T The weight of the thus treated tricot T was about 90% based on that of untreated tricot The tricot T was a very bulky knitted goods and had a natural fiber-like touch and gloss and an excellent Water absorbing property.

Example 7 Nylon-6 having an intrinsic viscosity of 1.15 in m-cresol at 30 C. and PET having an intrinsic viscosity of 0.61 in o-chlorophenol at 30 C. were mix spun by means of a spinneret as shown in FIG. 17 having seven mixer units (that is, the number n of stages of joining-dividing for layer-multiplying is 8), which was kept at a temperature of 290 C.

Namely, melted nylon-6 was fed into a reservoir R and melted PET was fed into a reservoir R in the same amount by means of gear pumps, respectively. Both the spinning materials were layer-multiplied in the spinneret, extruded through orifices 102 into air, cooled and wound up on a bobbin at a take-up rate of 700 m./min. after oiling. The thus wound undrawn filaments were drawn to 3.9 times their original length on a draw pin at 90 C. to obtain drawn filaments F of 70 denier of 18 filaments. The cross-section of the filament F had a nebulous segment structure as shown in FIG. 7.

The filaments F were formed into a skein and treated with 5% aqueous solution of sodium hydroxide at 95 C. for 3 minutes and 30 minutes to obtain multi-segmented filament F and filament F respectively. In the filament F 18% of PET were hydrolyzed and microscopial examination showed that a large number of ridges were observed on the surface. While, in the filament F 2, a major part of PET was hydrolyzed and nylon-6 was separated into very fine fibrils, which had a substantially circular cross-section having a diameter of about 1 (0.22,U.). Both the multi-segmented filaments F and F had a touch similar to that of natural fiber, particularly, that of wool, and further had a deep gloss. Moreover, the filament F was not only considerably bulky, but also extremely flexible. Such extremely flexible multi-segmented filaments are suitable for particular purposes, such as synthetic leather, typewriter ribbon, lens cleaner, thin special curtain, etc. In general multi-segmented filaments, such as the filaments F in which a part of polyester in the multi-layer portion is still remained, are superior in the resilience to the filaments P in which substantially all the polyester are removed, and can be preferably used for the production of cloths.

Example 8 Pellets of nylon-6 and PET used in Example 7 were mixed thoroughly in a ratio of 1/1. The mixture was kneaded and extruded through nozzles by means of a screw extruder kept at 290 C., cooled and cut into pellets of polymer blend (hereinafter abridged as NE). The pellets NE were spun through orifices on a spinneret plate kept at 290 C. in a conventional process, and the spun filaments were cooled, wound up on a bobbin at a take-up rate of 700 rn./min. after oiling, and drawn to 3.9 times their original length on a draw pin at 90 C. to obtain filaments F of 70 denier of 18 filaments.

The PET used in Example 7 was spun through orifices on a spinneret kept at 290 C. by a conventional meltspinning process, and the spun filaments were cooled, wound up on a bobbin at a take-up rate of 700 m./min.

after oiling, and drawn to 3.9 times their original length on a draw pin at C. to obtain filaments F of 70 denier of 18 filaments.

The multi-segmented filament F obtained in Example 7 and the above filaments F and F were knitted into half-stitched tricots T T and T by means of tricot knitting machine of 28 gauges, respectively. The tricots T T and T were subjected to a soaping in a conventional manner, dipped in 4% aqueous solution of sodium hydrOXide kept at C. for 20 minutes, washed with water, dyed and heat-treated under tension to obtain tricots T T and T respectively.

In the tricot T filaments were fibrillated and the tricot T had a silk-like touch and gloss.

In the tricot T filaments were considerably deteriorated and many broke portions were present. This is presumably due to the fact that components of the filament F was discontinuous and most of polyamide remained in the filament after alkali treatment were present in a granular or needle-like segment, and consequently the strength of the filament was decreased.

The tricot T as well as the tricot T had a waxy touch and a gloss inherent to synthetic fiber. This is presumably due to the fact that the filament P is hydrolyzed uniformly concentrically from the surface of the filament and has a relatively smooth surface.

Example 9 The nylon-6 and PET used in Example 7 were treated in the same manner as described in Example 7, except that a spinneret as shown in FIG. 17 having three mixer units, that is, having the number n of stages of joiningdividing of 4, to obtain filaments F of 100 denier of 36 filaments having a circular cross-section. The cross-section of the filament F had an archipclagic segment structure as shown in FIG. 6.

The nylon-6 used in Example 7, was extruded through orifices having a Y-shaped cross-section on a spinneret plate kept at 280 C. by a conventional melt-spinning process, cooled and wound up on a bobbin at a take-up rate of 700 m./ min. after oiling. The undrawn filaments were drawn to 3.8 times their original length to obtain filaments F of 100 denier of 36 filaments having a trilobal cross-section.

The filaments F and F were knitted into taffetas I and respectively. The tafietas 1 and had a waxy touch, and moreover the taffeta t had a sharp lightreflection gloss.

Then, the taffeta r was dipped in 5% aqueous solution to sodium hydroxide kept at 90 C. for 5 minutes to obtain a taffeta r Comparison of the weight of the untreated taffeta r and that of the thus treated tafieta I showed that 25% of polyester were hydrolyzed and removed. The taffeta t had a partially delustered deep gloss considerably different from the gloss of the taffeta Moreover, the taffeta t was considerably different from the taffeta r and L in the touch, and had no waxy touch inherent to synthetic fibers.

Example 10 Nylon-66 having an intrinsic viscosity of 1.1 in m-oresol at 30 C. and a copolymer of polyethylene terephthalate and polyethylene isophthalate in a weight ratio of 90/10, which had an intrinsic viscosity of 0.6 in o-chlorophenol at 30 C., were mix spun and drawn in the same manner as described in Example 7, except that a spinneret as shown in FIG. 17 having eleven mixer units (that is, the number n of stages joining-dividing is 12) was used, to obtain filaments F of S0 denier of 12 filaments. The cross-section of the filament F had a nebulous segment structure.

The nylon-66 and PET used in Example 7 were separately melted and fed into a spinneret kept at 290 C. The nylon-66 and the PET were arranged alternately as shown in FIG. 25 and extruded through orifices. The

extruded filaments were wound up on a bobbin in a conventional manner and then drawn to 3.9 times their original length on a draw pin at 90 C. to obtain filaments F of 50 denier of 12 filaments. When the filament F was dipped into hot water under tensionless state, the nylon-66 and the PET were separated into filaments (or segments) having a triangular cross-sectional shape.

The filaments F and F were knitted into taifetas I and 60, respectively. The tafieta 2 was treated in aqueous solution of sodium hydroxide kept at 80 C. for 20 minutes, washed with water and dried to obtain a tafieta r The taifeta 1 was washed with hot water and dried to obtain a tafieta 1 The taifeta 1 had a somewhat napped surface. The presence of naps on the surface of fabricated products is preferable for some purposes, and as the number n of stages of joining-dividing is larger at the spinning, the amount of the naps is larger. The taifeta t had a touch extremely similar to that of natural fiber and a fine and deep gloss. While, the tafieta r had a sharp, coarse and simple light-reflection gloss. In this case, the difierence between the taffeta r and the taffeta 1 in the touch and gloss. is presumably due to the difference between both taffetas in the shape and area of the cross-section of individual filaments (fibrils or segments) constituting the taffeta.

Example 11 The filaments F obtained in Example 1 were knitted into a knitted goods using a circular knitting machine having 200 needles, and the knitted goods was treated with an aqueous solution of formic acid or acetic acid having a predetermined concentration in a bath ratio of 500 under predetermined temperature and time conditions to obtain an acid treated knitted goods. In this acid treatment, the percentage of decreased weight of the knitted goods was determined. Furthermore, the water absorption percentage and the water absorption rate of the acid treated knitted goods were determined.

The obtained results are shown in the following Table 4 together with the treating conditions.

multiplied and spun. Namely, the two spinning materials were mix spun in a mixing ratio of 1/1 (weight ratio) by means of a spinneret as shown in FIG. 9 having the number n of stages of joining-dividing of 8 and drawn in the same manner as described in Example 1 to obtain filaments F of 85 denier of 20 filaments.

Although the filaments F were extruded through orifices 102 having a circular cross-section, but the microscopical examination showed that most of the cross-sections of the filaments F were somewhat deformed. This is presumably due to the diiference between the nylon-6 and the PET in the solidifying point and shrinking percentage.

The filament formed at a distance of 1 m. from the outlet of the orifice 102 had a particularly large cross-sectional area, which showed a distorted grainy structure.

Then, the above nylon-6 was fed into a conventional spinneret kept at 290 C., extruded through orifices having a circular or Y-shaped cross-section, cooled and wound up on a bobbin at a take-up rate of 600 .m./min. after oiling. The wound undrawn filaments were drawn to 3.92 times their original length to obtain drawn filaments F of 85 denier of 20 filaments having a circular cross-section or drawn filaments F of 85 denier of 20 filaments having a trilobal cross-section.

The above PET was spun and wound up in the same manner as described in the above nylon-6, and the resulting undrawn filaments were drawn to 3.92 times their original length on a draw pin at 100 C. to obtain drawn filament F of 85 denier of 20 filaments having -a circular cross-section or drawn filaments P of 70 denier of 18 filaments having a trilobal cross-section.

The filaments F were treated with 60%, 80% and 98% aqueous solutions of formic acid kept at 30 C. for 10 minutes to obtain multi-segmented filaments F F and F respectively. In the filament F 2.8% by weight of nylon-6 were hydrolyzed and a large number of ridges were observed microscopically on the surface. In the filament F about by weight of nylon-6 were hydrolyzed and fairly large amount of fibrils were formed. In the filament F most parts of nylon-6 were hydrolyzed and PET were substantially fibrillated.

TABLE 4 Treating condition Water Water Coneen- Temper- Decreased absorption absorption tratiou, ature, Time, weight, percentage, rate, Acid percent 0 hrs. percent percent min.

Not treated 5. 6 200 Treatment N o:

1.- Formic- 65 25 5 5.5 9. 5 2. 5 2 do 70 25 5 12. 5 19. 8 1. 5 3 d 80 25 5 33.3 34. 5 0. 5 4 90 25 5 38. 6 40. 5 0. 5 5 100 25 5 42. 7 49. 3 0. 5 6.. 70 25 2 9. 4 18. 7 1. 5 7.- 70 25 5 12. 5 19. 8 1 8.. 70 25 20 15. 8 23. 2 0. 5 9.. 70 25 20. 6 29. 6 0. 5 10 50 85 5 9. 7 15. 5 2 11 .-do 50 85 15 13.1 20. 0 0. 5 12 "do".-- 50 85 30 22. 7 28. 9 0. 5

Table 4 shows that when the polyamide component of filaments having multi-layer structure is dissolved and removed, the water absorbing property of the filaments in the knitted goods is improved.

The thus treated multi-segmented filaments had a somewhat delustered soft gloss, and the gloss became deeper with the proceeding of the treatment.

When the amount of polyamide removed was more than 5% base on the total weight of the knitted goods, the touch and water absorption rate of the multi-segmented filaments in the knitted goods were improved. When the amount was 1530%, the water absorbing property as well as the touch and gloss was remarkably improved. When the amount was more than 40%, the multi-segmented filaments were fabrillated to a relatively large extent, and had a strong gloss and a soft touch.

Example 12 The nylon-6 and PET used in Example 1 were layer- The multi-segmented filaments F P and 'F according to the present invention had a deep gloss similar to that of natural fiber, particularly, to that of silk. On the other hand, the control samples, i.e., the filaments F and F had a simple gloss inherent to synthetic fibers, and the filaments F and F had a sharp and metallic gloss entirely different from silk-like deep gloss. It will be apparent that although the filament F has a somewhat deformed circular cross-section as described above, the gloss of the multi-segmented filaments F F and F 310 is not caused by this deformed circular cross-sectional shape.

Example 13 The filaments F F and F obtained in Example 12 were knitted into half-stitched tricots T10, T and T respectively, using a tricot knitting machine of 28 gauges. The tricot T was subjected to a soaping in a conventional manner, dipped for 5 minutes in 80% aqueous solution of formic acid kept at 30 C. and washed with water. The

thus treated tricot T was dyed and subjected to a tenter finishing to obtain a tricot T The tricots T and T were dyed and subjected to a tenter finishing to obtain tricots T and T respectively.

The acid treated tricot T according to the present invention was 25% smaller than the untreated tricot T in the weight, and the multi-segmented filaments therein were partially formed into fibrils.

The tricot T had an excellent touch and gloss similar to those of natural fiber, particularly, those of silk. While, the control tricots T and T1200 as well as the tricots T and T had waxy touch and a metallic gloss inherent to filaments having a non-circular cross-section.

The water absorption percentage and water absorption rate of the tricots T T and T1200 were determined and a. result as shown in Table was obtained.

Table 5 shows that the tricot T obtained by the use of the filaments of the present invention is extremely excellent in the water absorbing property. This is presumably due to the segment microstructure (ridges, fibrils, etc.) characteristic to the filaments of the present invention.

Example 14 The filaments F F and F obtained in Example 2 were knitted info taffetas t r and t respectively.

The taffetas r and t had a waxy touch. The taffeta t had more improved and preferably touch than the taffetas t and r but the touch was still insuflficient.

The taffeta 1 was dipped in 80% aqueous solution of formic acid at 50 C. for 5 minutes in a bath ratio of 500 to dissolve and remove the nylon-6, whereby a taffeta T was obtained. Comparison of the weights of the taffetas T and T showed that substantially all (95%) of nylon-6 were dissolved and removed. The taffeta r according to the present invention had a partially delustered deep gloss different from sharp light-reflection gloss of control taffeta Moreover, the taffeta r was different from the taffeta and in the touch, and had no waxy touch inherent to synthetic fibers.

The water absorption percentage and water absorption rate of the taffetas r r r and t were determined in the same manner as described in Examples 11 and 12 and a result as shown in Table 6 was obtained.

TABLE 6 Water absorption Water percentage, absorption Taffeta percent rate, sec.

Table 6 shows that the taffeta t according to the invention is considerably superior in the water absorbing property to the control taffetas and r and to the untreated taffeta 1 Example 15 The tricot T obtained in Example 5 was treated for 30 minutes in 50% aqueous solution of acetic acid kept at 85 C., in a bath ratio of 500 to obtain a tricot T The weight of the thus treated tricot T was about 25% smaller than that of untreated tricot T The tricots T and T prepared from synthetic filaments of the present invention had a satisfactory touch, gloss and water absorbing property.

20 Example 16 The tricot T prepared in Example 6 was dipped for 10 minutes in 50% aqueous solution of acetic acid kept at C. to obtain a tricot T The weight of the thus treated tricot T was about 10% smaller than that of untreated tricot T The tricots T and T were very bulky knitted goods and had a natural fiber-like touch and gloss and an excellent wafer absorbing property.

Example 17 Nylon-6 having an intrinsic viscosity of 1.15 in mcresol at 30 C. and PET having an intrinsic viscosity of 0.61 in o-chlorophenol at 30 C. were mix spun. A spinneret as shown in FIG. 17 having eight mixer units (that is, the number n of joining-dividing is 9) was used, and the temperature of the spinneret was kept at 290 C. Melted nylon-6 was fed into a reservoir R and melted PET was fed into a reserovir R in a feed ratio of 1/ 1. The two spinning materials were layer-multiplied in the spinneret and the layer-multiplied spinning materials were spun through orifices 102 having a diameter of 0.25 mm., cooled and wound up on a bobbin at a take-up rate of 700 m./min. after oiling. The undrawn filaments were drawn to 3.8 times their original length on a draw pin at C. to obtain drawn filaments Y of denier of 24 filaments.

For the comparison, pellets of the above PET and nylon-6 were mixed in a ratio of 1/ 1, and the mixture was melted and spun through a screw extruder to form filaments which were drawn to obtain drawn filaments Y of 100 denier of 24 filaments. In the same manner, drawn filaments Y were produced from PET alone, and drawn filaments Y were produced from nylon-6 alone. In the filaments Y Y and Y the spinning and drawing were very easy, but in the filament Y both of the spinning and drawing were very difficult and yarn breakage occurred very often.

The above filaments Y -Y were knitted into knitted goods K K respectively, using a circular knitting machine having 200 needles. Each of the knitted goods was washed to remove oil and water-soluble component, and treated with an aqueous solution of formic acid having a concentration as shown in the following Table 7 at room temperature. The treating condition and the percentage of decreased weight of the knitted goods during this formic acid treatment are shown in Table 7.

TABLE 7 Treating condition Decreased weight of Concentration knitted goods, percent of formic acid, Time,

No. percent min. K1 K2 K; K

In the knitted goods K treated under the above conditions Nos. 3 and 4, considerably a large amount of polymer flocks was fallen off, and the strength of the treated knitted goods lowered.

Then, the thus treated knitted goods were determined with respect to their water absorption percentage and water absorption rate, and results are shown in the following Tables 8 and 9. In Table 9, 0 second of water absorption rate means less than 0.5 second."

TABLE 8 Water absorption, percentage Sample K1 K2 K3 4 Not treated 6. 1 6. 0 2 6 9. 3 No.1 9.8 8.5 2 5 9.1

TABLE 9 Water absorption rate, sec.

Sample K1 K2 s 4 Not treated 200 200 200 200 N0. 1 1. 200 200 200 No. 2 0.8 100 200 200 No. 3 0 200 100 No. 4 0 200 It can be seen from Table 8 that the knitted goods K treated according to the present invention has extremely excellent water absorbing property. When an amount of polyamide removed in 6% by weight based on thetotal weight of the knitted goods, the touch and the water absorption rate are improved, and when the removed amount is about by weight, the water absorption percentage is remarkably increased in addition to 'the increase of water absorption rate and further the touch and gloss are improved. When the removed amount is more than 40% by weight, the fibers are considerably fibrillated and have considerably strong gloss and soft touch.

'On the other hand, in the control 'knitted goods K and K the water absorbing property, touch and gloss are not improved substantially. In the control knitted goods K the strength considerably lowers with the removal of polyamide, and the knitted goods are worn into tatters. Furthermore, the water absorbing property, touch and gloss are not substantially improved.

Example 18 Nylon-66 having an intrinsic viscosity of 1.1 in mcresol at C. and PET used in Example 17 were mix spun using a spinneret as shown in FIG. 11 having five mixer units (that is, the number n of joining-dividing is 6), and drawn in the same manner as described in Example 17 to obtain drawn filaments Y of 50 denier of 12 filaments. The cross-section of the filament Y had an archipelagic structure.

The filaments Y were knitted into a taffeta t and the talfeta t was treated for 20 minutes in 60% aqueous solution of acetic acid kept at 85 C., washed with water and dried to obtain a tatfeta t The water absorption percentage and water absorption rate of the talfetas l ,t and I produced in Example 10 are shown in the following Table 10. i

TABLE 10 Water absorption Water percentage, absorption percent rate, sec.

Taffeta:

t (not treated) 5. 4 200 t r (present invention) 20. 3 0. 5

t (control) 6. 2 200 Table 10 shows that the fiber according to the present invention, i.e., the taffeta I is excellent in the water absorbing property.

Moreover, the tafreta had a touch extremely similar to that of natural fiber and a fine and deep gloss. While, the taffeta 1 had a coarse, simple and sharp light-refiection gloss.

The difference between the taffeta i and the tatfeta t in the touch and gloss is presumably due to the crosssectional shape and size of individual filaments (fibrils or segments) constituting these taffetas.

Example 19 As a control, the same PET as used in Example 17 was spun through orifices having a Y-shaped cross-section .on a spinneret plate kept at 290 C., by a conventional meltspinning process and the spun filaments were cooled and wound up on a bobbin after oiling. The undrawn filaments were drawn to 3.8 times their original length on a draw pin at 110 C. to obtain drawn filaments Y, of 100 denier of 36 filaments having a trilobal cross-section.

The filaments Y and Y were knitted into tricots T and T respectively. Both the trieots T and T had a waxy touch, but the tricot T had a sharp light-reflection gloss.

The tricot T was treated for 5 minutes in 75% aqueous solution of formic acid kept at 30 C. to obtain a tricot T The weight of the tricot T was 30% smaller than that of the tricot T The water absorption percentage'and the water absorption rate of the tricots T T and T are shown in the following Table 11.

Table 11 shows that the multi-segmented fiber structure according to the present invention, i.e., tricot T is extremely excellent in the water absorbing property.

The tricot T had a partially delustered deep gloss considerably diiferent from gloss of the tricot T Moreover, the tricot T was considerably different from the tricots T and T17 in the touch, and had no waxy touch inherent to synthetic fibers.

What is claimed is:

1. A synthetic multi-segmented fiber characterized by having a touch similar to natural fiber, an excellent water absorbing property, and an improved gloss, comprising a finely segmented component and a homogenous component consisting of a single fiber-forming polymer, both components being bonded and extending continuously along the longitudinal direction of the fiber,

said finely segmented component consisting of at least 10 fine segments composed of at least one component of fiber-forming linear polyamide and polyester, extending substantially continuously along the longitudinal direction of the fiber and occupying at least a part of the periphery of the unitary multi-segmented fiber, said fine segments having cross-sectional shapes and areas irregular and uneven to each other, and forming ridges with an average space therebetween of at least 0.1/L in adjacent ones at least on the periphery of the unitary multi-segmented fiber or being fibrillated, which is formed by layer-multiplying melted fiber-forming linear polyamide and polyester through repeated steps of joining-dividing in diiferent phase on a substantial plane into distorted grainy, nebulous or archipelagic multi-segmented structure,

spinning said layer-multiplied component and said homogeneous component at the same time through common spinning orifices,

treating the spun fibers with an alkali or an acid to decompose, and

removing at least a part of the polyester or polyamide.

2. The fiber as claimed in claim 1, wherein said average space is 0.1 to la.

3. The fiber as claimed in claim 1, wherein said fine segments have flat cross-sectional shape.

4. The fiber as claimed in claim 1, wherein said crosssectional shapes have an average dimension of 0.1 to 10p.

5. The fiber as claimed in claim 1, wherein said cross- 7 5 sectional shapes have an average dimension of 0.1 to 1]! 6. The fiber as claimed in claim 1, wherein the number of said fine segments is to 100.

7. The fiber as claimed in claim 3, wherein the number of said fine segments is 100 to 10,000.

8. The fiber as claimed in claim 1, wherein the finely segmented component surrounds the homogeneous component.

9. The fiber as claimed in claim 1, wherein the finely segmented component and the homogeneous component are arranged in a side-by-side relation.

10. The fiber as claimed in claim 1, wherein the unitary multi-segmented fiber has a non-circular cross-section.

11. The fiber as claimed in claim 3, wherein at least five ends of the fine segments having the fiat cross-sectional shape expose to the surface of the unitary multi-segmented fiber.

12. The fiber as claimed in claim 3, wherein at least 20 ends of the fine segments having the fiat cross-sectional shape expose to the surface of the unitary multi-segmented fiber.

13. The fiber as claimed in claim 1, wherein said fine segments forming the periphery of the fiber have been fibrillated.

14. The fiber as claimed in claim 1, wherein substantially all of said -fine segments have been fibrillated.

15. The fiber as claimed in claim 1, wherein said fine segments consist of fiber-forming linear polyamide and polyester.

16. The fiber as claimed in claim 1, wherein said fine segments consist of a fiber-forming linear polyamide.

17. The fiber as claimed in claim 1, wherein said fine segments consist of a fiber-forming linear polyester.

18. The fiber as claimed in claim 1, wherein said homogeneous component consists of a polyamide.

19. The fiber as claimed in claim 1, wherein said homogeneous component consists of a polyester.

20. The fiber as claimed in claim 18, wherein said finely segmented component consists of a polyamide.

21. The fiber as claimed in claim 18, wherein said finely segmented component consists of a polyester.

22. The fiber as claimed in claim 1, wherein said fine segments consist of polyamide and polyester in a mixing ratio of 1:10 to 10:1 by weight.

23. The fiber as claimed in claim 1, wherein said fine segments consist of polyamide and polyester in a mixing ratio of 1:3 to 3:1 by weight.

24. The fiber as claimed in claim 1, wherein said polyamide is nylon-6 or nylon-66.

25. The fiber as claimed in claim 1, wherein said polyester is polyethylene terephthalate or polyethylene oxybenzoate.

26. The fiber as claimed in claim 1, wherein said segments are not fibrillated and said ridges are formed between adjacent segments on the periphery of the multisegmented fiber.

27. The fiber as claimed in claim 1, wherein said ridges are formed between a part of adjacent segments on the periphery of the multi-segmented fiber and remaining segments are not fibrillated.

28. The fiber as claimed in claim 1, wherein each segment of the multi-segmented fiber is completely fibrillated.

References Cited UNITED STATES PATENTS 3,531,368 9/1970 Okamoto et al. 161-175 2,700,657 1/1955 Luk et al. 264Dig. 29 UX 2,531,234 11/1950 Seckel 264-Dig. 29 3,097,991 7/1963 Miller et a1 264Dig. 29 3,323,978 6/1967 Rasmussen 264Dig. 29 3,402,097 9/1968 Knudsen et a1. 264Dig. 29 3,447,308 6/1969 Fontun et al 264Dig. 29 3,577,308 5/1971 Van Drunen et al. 161-176 FOREIGN PATENTS 1,167,182 10/1969 Great Britain 264Dig. 29 1,579,231 8/1969 France 264Dig. 29 1,495,835 8/1967 France 264Dig. 29

ROBERT F. BURNETT, Primary Examiner R. O. LINKER, JR., Assistant Examiner U.S. Cl. X.R. 

